In storage apparatuses, in order to realize power saving, apparatuses in which a technology called massive array of idle disks (MAID) is mounted are known.
In the MAID, hard disk drives (HDD) in which any data access does not occur are stopped, and only HDDs in which data accesses occur are operated, whereby the power consumption is reduced.
In addition, a technique called an ecological mode is known in which power saving is achieved by managing the schedules of operation times of HDDs using the MAID.
In the ecological mode, a period of a time in which a power saving operation is executed is set by a user in advance as an ecological schedule, and the power saving operation is executed according to this ecological schedule.
In the power saving operation in the ecological mode, there are two kinds of modes including a motor-off (M-off) mode and a power-off (P-off) mode.
In the motor-off mode, by stopping a motor rotating a platter on which data is recorded, the power consumption is reduced. On the other hand, in the power-off mode, by stopping the supply of power to an HDD, the power consumption is reduced more than that of the motor-off mode.
However, in such conventional storage apparatuses, in a case where redundant arrays of inexpensive disks (RAID) are configured, a user needs to set validness/invalidness of the ecological mode in units of RAIDS. In addition, in a case where the ecological mode is set to be valid, the user needs to set presence/absence of an ecological schedule, and settings of a way of switching between the power-off mode and the motor-off mode in the period of an ecological schedule time and the like need to be made as well. In other words, the user needs to execute various setting operations relating to the ecological mode and the like, which is complicated.
In addition, as another technology for realizing power consumption, a rotation speed-changeable HDD that is an HDD capable of changing the rotation speed of a platter is known. Thus, by efficiently using such a rotation speed-changeable HDD, power saving is expected to be realized in a simple manner.    [Patent Literature 1] Japanese Laid-open Patent Publication No. 2009-3831    [Patent Literature 2] Japanese Laid-open Patent Publication No. 2000-100054    [Patent Literature 3] Japanese Laid-open Patent Publication No. 2006-40437    [Non Patent Literature 1] Shingi Hashimoto, “Will large-volume low-energy-consumption HDD develop a new market?”, DOS/V POWER REPORT, www.dosv.jp/other/0712/12.htm, [searched Dec. 17, 2014]